This casserole is ridiculously good! I got the idea from WebMD's recipe for Pesto Zucchini Tomato Gratin. The picture shows it on top of pesto penne but didn't say anything about cooking the gratin with the penne. I decided to combine the two and turn it into a casserole. This makes a lot so you'll have plenty of leftovers.

My husband hates Zucchini and while it's not my favorite vegetable either I am determined to sneak it into as many dishes as I can. I shred the zucchini to make it more palatable. It works really well in this casserole!

Pre-heat your oven to 375 degrees. Fill a large pot with water, cover with lid and heat to a boil.

Shred your zucchini and slice your plum tomatoes into thin slices (I remove the jelly and seeds as much as I can). Set aside.

Add a drizzle of extra light olive oil to a large skillet and heat. Once the oil starts to sizzle, add the shredded zucchini. While that's cooking, add the penne and some salt to the boiling water and cook 10-12 minutes based on package instructions. While the penne is cooking, continue cooking the zucchini. Stir occasionally. You want to dry out the zucchini a bit so there is not so much water. After 10 minutes, stir in 2 tablespoons of the pesto. Set aside.

In a bowl, add the 2 cups of panko bread crumbs and about 3 tbsps of extra light olive oil and mix.

Drain the pasta reserving 1/2 cup of pasta water. Add the remaining pesto to the pasta and add the 1/2 cup of pasta water. Stir until all the pasta is coating in pesto.

In a 11 X 13 baking dish, add the pasta. Cover the top of the pasta with the shredded zucchini pesto mix. Top with half of the panko bread crumbs. Then add a layer of sliced tomatoes. Top with the pearl mozzarella balls and the rest of the panko.

Cover with aluminum foil and add to center rack of oven. Cook for 20 minutes. Remove foil, switch oven to low broil and broil for a couple minutes until the top gets brown. If you have patience, you can wait a little longer and it'll brown on top in the 375 degree oven. I am not patient so I like to brown with a quick broil. Watch the casserole closely or you can burn the top!

Let sit for about 10 minutes before serving. Or dive in if you can't wait.